I had to bring this up after reading the post on 3 dead trainers. A test pilot is someone willing to test your newly built or repaired plane. Be careful here, all flying fieldS are full of these guys or gals. If they are a little too eager to test your plane, then I would stay away from them as a potential candidate. An instructor could also test planes as well, but if either doesn't tear into your aircraft like an FAA inspector, then I would kindly avoid them as your test pilot. A good instructor is someone who teaches and the first lesson should be to slow down. If you think you are an instructor, I would ask that you take a good look at yourself and your techniques to ensure you don't discourage those that just want to learn. I have met many pilots who simply call themselves test pilots rather than instructors. A teacher as we can all agree, takes a certain skill. Agressive and arrogant aren't the traits for a good instructor.
I recently taught a friend of mine to fly and he immediately bought a few planes which I knew he was not ready for. Every time he brought his new creation out to the field he wanted me to test fly it. Each time we had to make adjustments or we downed the plane so he could make repairs or adjustments. The plane in question is an Ultimate Bipe w/.40FX that has still not flown. Not good right after a trainer. Just making the point that if you are new to the hobby, try to realize that flying aircraft takes care, patience and attention to detail. I tell anyone I'm teaching that they need to look at these models as if they were scale aircraft. A scale Cessna 172 can kill one person and so can an out of control R/C trainer heading for the pits. I'm not trying to plant a bad picture of R/C aircraft. Only that I have seen the many new comers jump at the prospect of at least seeing their creation fly at the hands of a person who thinks he has the necessary skills to fly an untested aircraft. They then blame a hit or faulty building after the crash and the newcomer leaves the field with a garbage bag full of parts. [&o]
I'm dieing to see my friends bipe fly, but until it is truly ready, I'm not willing to risk it. [8D]

These are thing that I check before flying an untested plane.

Check list:

check balance
Structure
electrical connections and routing(seating, foaming, servo extensions etc.)
check battery(test pilot should ask how old the radio sysytem is)
check all control surfaces and throttle linkage for smooth operation
check control horns, locks installed or fuel line to keep linkage from disconnecting
check fuel system for leaks or restrictive fuel lines
motor mount integrity
engine performance(smooth transition and good idle)
Taxi test
Back to pits and inspect(linkages, etc.)



My 2 cents.